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03/24/12 13:33
  03/24/12 13:41

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#186864 - Interrupts, the 8052 & Solenoids
Hi all,

Designed and built this project on a breadboard and everything worked accordingly but I am now having issues with it on the PCP board. The interrupt is triggered by an external circuit that detects smoke. It is is an edge triggered interrupt - smoke detected, interrupt pin goes low and interrupt routine begins.

Problem is - even without this external circuit connected the interrupt is being triggered by the solenoids. The solenoids are driven by the relays. When I disconnect solenoid from circuit and the relays are energised eveything is okay. When I connect the solenoids the following happens;

Relay energises and solenoid plunger retracts. It is fine to this point. When the programmed time has elapsed and the relay is no longer energised, the solenoid plunger is released but this then triggers the 89s52's interrupt routine.

The solenoids both have their own power and ground. Help please?

List of 12 messages in thread
Interrupts, the 8052 & Solenoids      Cian Young      03/24/12 13:33      
   Freewheeel diodes      Per Westermark      03/24/12 15:00      
      ULN2003a      Cian Young      03/24/12 18:34      
         more than one inductive load here      Jim Granville      03/24/12 19:11      
            Solenoids      Cian Young      03/24/12 19:26      
               diode choices      Jim Granville      03/24/12 19:42      
         Diodes in ULN2003a      Michael Karas      03/25/12 08:21      
         Within this chip      Erik Malund      03/26/12 07:03      
            Do I hear...      Michael Karas      03/26/12 07:07      
   Irish keypad layout!!      Andy Neil      03/25/12 06:27      
   Lack of resistors.      Michael Karas      03/26/12 08:00      
      Success      Cian Young      03/28/12 11:00      

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